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Tag Air Spring Pressure

I seem to remember seeing on air diagrams, a regulator and gauge for the pressure to the tag air springs (bags).  There is one on the steer air springs.  I am at my friends shop for a few days and we got under the rear, found the two six packs but no regulator to the tab springs.  Anyone with a 2001 42 foot tag coach know how to adjust the tag air spring pressure?

In talking to more knowledgeable folks than myself, I am told increasing tag pressue puts more weight on the steer axle and reducing the tag pressure removes weight from the steer axle.  Thanks for responding to my inquiry, a bunch.
Rudy Legett
2003 U320 4010 ISM 450 hp
2001 U320 4220 ISM 450 hp
1995 U320 M11 400 hp
1990 Granvilla 300 hp 3208T
Aqua Hot Service Houston and Southeast Texas

Re: Tag Air Spring Pressure

Reply #1 –
Quote from: Rudy –
I am told increasing tag pressure puts more weight on the steer axle and reducing the tag pressure removes weight from the steer axle. 

Correct.  Adding more air pressure to the tag air bags/carrying more weight on the tag will ADD weight to the front axle and REMOVE weight from the drive axle.

Ideal is for each axle to be loaded to the same percent of its GAWR.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Tag Air Spring Pressure

Reply #2 –
We can find no requlator to adjust this pressure which would say the pressure in the drive springs is the same for the tag springs.  Does that sound correct for this coach?
Rudy Legett
2003 U320 4010 ISM 450 hp
2001 U320 4220 ISM 450 hp
1995 U320 M11 400 hp
1990 Granvilla 300 hp 3208T
Aqua Hot Service Houston and Southeast Texas

Re: Tag Air Spring Pressure

Reply #3 –
Wouldn't the ride height control valves regulate the pressure to both the tag and drive axles? Not sure you would want to fiddle with this setting.
I believe the regulator on the steer axle just adjusts pressure for the air springs to control the speed that the front raises. Again the ride height valve controls the pressure when the vehicle is being driven.
At least that's the way I think it works.
Steve & Sandy
2003 U320 4220 WCDS, build#6160
Motorcade #17794
USMC '67-'71

Re: Tag Air Spring Pressure

Reply #4 –
Quote from: SteveB –
Wouldn't the ride height control valves regulate the pressure to both the tag and drive axles? Not sure you would want to fiddle with this setting.
I believe the regulator on the steer axle just adjusts pressure for the air springs to control the speed that the front raises. Again the ride height valve controls the pressure when the vehicle is being driven.
At least that's the way I think it works.


So, is there a separate ride height valve for the tag axle?  That is certainly one way to regulate ride height/PSI.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: Tag Air Spring Pressure

Reply #5 –
Only one set of ride height valves for the rear of coach, one on each side for side to side adjustment.  There are two 6 pack manafolds, one for drive and one for tags.
Rudy Legett
2003 U320 4010 ISM 450 hp
2001 U320 4220 ISM 450 hp
1995 U320 M11 400 hp
1990 Granvilla 300 hp 3208T
Aqua Hot Service Houston and Southeast Texas

Re: Tag Air Spring Pressure

Reply #6 –
Well, I believe I have found the correct HWH air diagram for my coach.  It does not show a regulator for the tag bags.  So, that question is answered.
Rudy Legett
2003 U320 4010 ISM 450 hp
2001 U320 4220 ISM 450 hp
1995 U320 M11 400 hp
1990 Granvilla 300 hp 3208T
Aqua Hot Service Houston and Southeast Texas

Re: Tag Air Spring Pressure

Reply #7 –
I know different systems but on the IH45  when sitting just after travel position is taken the tag bags do not have as much air as the  drive. The drive axle has 4 bags to carry the weight vs the 2 for the tags  ie 98 tag  68 drive. I have no idea how they adjust the pressures on the mechanical coaches.
2014 ih45  (4th Foretravel owned)
 1997 36' U295 Sold in 2020, owned for 19 years
  U240 36' Sold to insurance company after melting in garage fire
    33' Foretravel on Dodge Chassis  Sold very long time ago